Introduction

Scepticism is as much the result of knowledge, as knowledge is of scepticism. To be content with what we at present know, is, for the most part, to shut our ears against conviction; since, from the very gradual character of our education, we must continually forget, and emancipate ourselves from, knowledge previously acquired; we must set aside old notions and embrace fresh ones; and, as we learn, we must be daily unlearning something which it has cost us no small labour and anxiety to acquire.

And this difficulty attaches itself more closely to an age in which progress has gained...